As part of the new anaerobic digestion site the anaerobic digester required a chemical resistant tank lining to protect the gas space from hydrogen sulphide attack and form a gas seal.
Initially the concrete was prepared by method of high pressure washing to remove laitance and contaminants – essential for ensuring excellent adhesion of the tank lining system.
Sealing the tank panel joints
To seal the tank panel joints, either side of the joints was primed using Remmers Epoxy MT100 moisture tolerant epoxy primer. The joints were then bridged using a foil de-bonding tape. Corrolastic highly chemical resistant tank lining polyurea was then spray applied over these tapes, overlapping on to the concrete either side of the joint. This fully seals the tank and makes the tank lining gas tight – essential for the containing the anaerobic digestion product – valuable methane gas.
This was followed by the application of Remmers Epoxy MT100 damp tolerant epoxy primer. This ensures excellent adhesion to the substrate which is of critical importance for any tank lining. Once cured Remmers Epoxy Universal was applied throughout the tank by method of airless spray. This excellent material can crack bridge up to 0.2mm which is beyond the expected cracking of the concrete.
To deal with the numerous blow holes in the concrete substrate a chopped fibreglass strand was incorporated in the first coat of Remmers Epoxy Universal to create a seamless tank lining. A single pin hole or blow hole is a point of failure in a tank lining and the concrete below will be attacked – something most clients and inferior contractors seem to overlook.
Testing the lining
The lining was tested using a DC holiday spark tester. This checks for pin holes and where found they can be touched in by brush. This is perhaps the most important stage of the lining process as a single pin hole in an aggressive environment will lead to the failure of the tank lining.
As part of the contract we also weather sealed the external tank panel joints using SikaHyflex 250 Facade. This UV stable polyurethane sealant will ensure the tank remains water tight for the foreseeable future.
The site manager was extremely please with the completed works and praised our team for all of their hard work to deliver the project on time which included weekend working and a few long days.